get rid of pointless allocations and copying in ecryptfs_follow_link()

switch to generic_readlink(), while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 9 insertions, 39 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index ab35b113003..a07441a0a87 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -660,11 +660,10 @@ static int ecryptfs_readlink_lower(struct dentry *dentry, char **buf,
 {
         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
         char *lower_buf;
-        size_t lower_bufsiz = PATH_MAX;
         mm_segment_t old_fs;
         int rc;
 
-        lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
+        lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
         if (!lower_buf) {
                 rc = -ENOMEM;
                 goto out;
@@ -673,58 +672,29 @@ static int ecryptfs_readlink_lower(struct dentry *dentry, char **buf,
         set_fs(get_ds());
         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
                                                    (char __user *)lower_buf,
-                                                   lower_bufsiz);
+                                                   PATH_MAX);
         set_fs(old_fs);
         if (rc < 0)
                 goto out;
-        lower_bufsiz = rc;
         rc = ecryptfs_decode_and_decrypt_filename(buf, bufsiz, dentry,
-                                                  lower_buf, lower_bufsiz);
+                                                  lower_buf, rc);
 out:
         kfree(lower_buf);
         return rc;
 }
 
-static int
-ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
+static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-        char *kbuf;
-        size_t kbufsiz, copied;
+        char *buf;
+        size_t len = PATH_MAX;
         int rc;
 
-        rc = ecryptfs_readlink_lower(dentry, &kbuf, &kbufsiz);
+        rc = ecryptfs_readlink_lower(dentry, &buf, &len);
         if (rc)
                 goto out;
-        copied = min_t(size_t, bufsiz, kbufsiz);
-        rc = copy_to_user(buf, kbuf, copied) ? -EFAULT : copied;
-        kfree(kbuf);
         fsstack_copy_attr_atime(dentry->d_inode,
                                 ecryptfs_dentry_to_lower(dentry)->d_inode);
-out:
-        return rc;
-}
-
-static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-        char *buf;
-        int len = PAGE_SIZE, rc;
-        mm_segment_t old_fs;
-
-        /* Released in ecryptfs_put_link(); only release here on error */
-        buf = kmalloc(len, GFP_KERNEL);
-        if (!buf) {
-                buf = ERR_PTR(-ENOMEM);
-                goto out;
-        }
-        old_fs = get_fs();
-        set_fs(get_ds());
-        rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
-        set_fs(old_fs);
-        if (rc < 0) {
-                kfree(buf);
-                buf = ERR_PTR(rc);
-        } else
-                buf[rc] = '\0';
+        buf[len] = '\0';
 out:
         nd_set_link(nd, buf);
         return NULL;
@@ -1153,7 +1123,7 @@ out:
 }
 
 const struct inode_operations ecryptfs_symlink_iops = {
-        .readlink = ecryptfs_readlink,
+        .readlink = generic_readlink,
         .follow_link = ecryptfs_follow_link,
         .put_link = ecryptfs_put_link,
         .permission = ecryptfs_permission,